// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
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// modification, are permitted provided that the following conditions
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//    notice, this list of conditions and the following disclaimer in the
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//    this software without specific prior written permission.
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package org.objectweb.asm;

/**
 * An edge in the control flow graph of a method. Each node of this graph is a basic block, represented with the Label corresponding to its first instruction. Each edge goes from one node to another, i.e. from one basic block to another (called the predecessor and successor blocks, respectively). An edge corresponds either to a jump or ret instruction or to an exception handler.
 *
 * @see Label
 * @author Eric Bruneton
 */
final class Edge {

	/**
	 * A control flow graph edge corresponding to a jump or ret instruction. Only used with {@link ClassWriter#COMPUTE_FRAMES}.
	 */
	static final int JUMP = 0;

	/**
	 * A control flow graph edge corresponding to an exception handler. Only used with {@link ClassWriter#COMPUTE_MAXS}.
	 */
	static final int EXCEPTION = 0x7FFFFFFF;

	/**
	 * Information about this control flow graph edge.
	 *
	 * <ul>
	 * <li>If {@link ClassWriter#COMPUTE_MAXS} is used, this field contains either a stack size delta (for an edge corresponding to a jump instruction), or the value EXCEPTION (for an edge corresponding to an exception handler). The stack size delta is the stack size just after the jump instruction, minus the stack size at the beginning of the predecessor basic block, i.e. the one containing the jump instruction.
	 * <li>If {@link ClassWriter#COMPUTE_FRAMES} is used, this field contains either the value JUMP (for an edge corresponding to a jump instruction), or the index, in the {@link ClassWriter} type table, of the exception type that is handled (for an edge corresponding to an exception handler).
	 * </ul>
	 */
	final int info;

	/** The successor block of this control flow graph edge. */
	final Label successor;

	/**
	 * The next edge in the list of outgoing edges of a basic block. See {@link Label#outgoingEdges}.
	 */
	Edge nextEdge;

	/**
	 * Constructs a new Edge.
	 *
	 * @param info
	 *          see {@link #info}.
	 * @param successor
	 *          see {@link #successor}.
	 * @param nextEdge
	 *          see {@link #nextEdge}.
	 */
	Edge(final int info, final Label successor, final Edge nextEdge) {
		this.info = info;
		this.successor = successor;
		this.nextEdge = nextEdge;
	}
}
